Simplify the following expression: $z = \dfrac{-2y + 1}{5y + 6} - \dfrac{-9y + 5}{5y + 6}$
Explanation: Since the expressions have the same denominator we simply subtract the numerators: $z = \dfrac{-2y + 1 - (-9y + 5)}{5y + 6}$ Distribute the negative sign: $z = \dfrac{-2y + 1 + 9y - 5}{5y + 6}$ Combine like terms: $z = \dfrac{7y - 4}{5y + 6}$